The collapse of Rome, at least the Western Roman Empire, is marked when in 476 AD a Germanic soldier deposed the last emperor Romulus Augustulus. A multitude of reasons have been put forward: from moral decay and political instability to Germanic tribes and peasant revolts, malaria and lead poisoning. One rarely cites unsustainable food policies as one of the essential causes. Since the Roman conquest of Gaul in the first century, they introduced Southern cash crops to Northwest Europe, replacing or marginalizing the local crops. With the end of the so-called Roman Warm Period, the agriculture collapsed along with the local economy. Rome refused to modify its food policies and half-starved Roman military could no longer control the Northern regions, which revolted in a series of successions.
In the 17th century at the height of the Renaissance, Paris was one of the largest and most important metropolitan centers in Europe. The architecture of Paris saw a dominating rise of classicism and urbanism on a gargantuan scale. Man was proclaimed to stand above nature and it was no more apparent than in the design of the gardens of Versailles: the aviaries, menageries and fountains were not just a mere exhibition of wealth, but an implication of the mighty man’s control over nature. During their heydays, the Gardens consumed more water than the entire population of Paris. The implemented water projects ranged from raising waters of the Seine to diverting the river Bievre and building a 160 km long aqueduct, eventually draining the King’s treasury.
These two historical moments illustrate the workings of Liebig’s Law or the Law of the Limiting Factor – Any system at any time has at least one factor that limits its expansion or survival. Failure to recognize this seemingly insignificant factor at the time brought the mightiest of empires to their knees and vanquished great civilizations. Yet again, the adamant conviction that humanity is capable of engineering its way out of any ecological crisis makes us fail to fully address the calamity of our technological practices.
Nowhere it is more evident than in the AC industry, which is locked in a downward spiral of a positive feedback loop: heavy use of energy from the cooling technology sector contributes to warming of the climate, which in return, increases the global cooling demand, which negatively affects the climate and so on.
Cooling is essential in the modern world. Air conditioning has become an integral part of our society. It is the backbone of the industrial development, infrastructure, food production and technological progress. Like many other good things in life, it comes at a high cost. Traditional AC systems are based on high-energy demanding mechanical vapor compression (MVC) technology that utilizes refrigerants as cooling media (the greenhouse agents that cause ozone layer depletion and have an impact on global warming thousands times more severe than CO21). And while the COP of the most advanced MVC systems hovers under a mere factor of 4, little room for innovations is left to increase efficiency of Carnot Cycle heat pumps.
Nature has crafted a much more efficient way to remove heat from a system through the adiabatic process of water evaporation. Humanity has been taking advantage of this process for millennia and evaporative cooling has become an integral part of the modern world. Many industries heavily depend on it and a fountain design of cooling towers has become a common feature of modern architecture.
In the 70s in the seaside city of Odessa in Ukraine, a few academics pushed the efficiency of the evaporative cooling process to its full thermodynamic potential and introduced the Dew Point evaporative cooling system, that allowed to achieve much lower temperature of the processed air while keeping it dry. Despite the potential, Dew Point evaporative cooling technology plays a marginal role today in the AC industry: a number of design-inherited flaws such as a complex Heat Mass Exchangers (HMX) and a reduced airflow potential narrow the range of applications and make the cost premium too high for the added efficiency. It’s worth noticing that critics of evaporative cooling technology point out that it requires more than 2 liters of water to produce 1 kW/h of cold. However in comparison, a typical power generating plant wastes 30-70 liters of water in a cooling tower to yield 1kW/h of electricity2.
Another approach to maximize the potential of evaporative cooling has been taken by Air2O, An Innovative Cooling Company. At its heart, Air2O uses a two stage indirect evaporative cooling solution. During the first stage, outdoor air is passed through the evaporative cooling section, and as the warm air is cooled, so is the water. This cool water is then transferred to a high efficiency heat exchanger (over which the primary outdoor air is passed) to deliver the first stage of cooling with no additional moisture; this is indirect evaporative cooling. The air is then further cooled as it passes the second cooling stage; direct evaporative cooling. This same concept can also be utilized to provide ultra-efficient heat recovery of air-conditioned buildings. The combination of these two stages delivers the highest performing evaporative cooling system available in the world today.
Air2O has a unique ability to adapt and become a hybrid cooling system, incorporating traditional refrigerant or chilled water-cooling coils. Air2O’s equally unique and intelligent control system can automatically respond to external weather conditions, switching its cooling strategy from evaporative cooling to air-conditioning when needed. This ensures consistent performance, high efficiency and significant energy savings. This means that the leading Air2O hybrid cooling technology can be applied anywhere in the world, providing energy efficient cooling without compromise3.
Air2O technology is capable of reaching COP over 30 and it can save up to 80% of the electrical energy compared to traditional MVC systems. The US alone consumed an astonishing 1,000 Terawatt/hr. for cooling and refrigeration needs in 2018 4.
Space cooling is increasingly taking a higher percentage of energy costs. In view of the current global warming trend and the accelerated global industrial development, cooling energy demand, especially in urban regions, has been rising significantly. This has resulted in a growth rate of 43% for space cooling energy over the last decade, which by far exceeds the growth in both population (13%) and building floor area (34%)5. In comparison, the global evaporative cooling market was valued at €4.48 billion in 2015, and is projected to reach €5.95 billion by the end of 2020. At the CAGR of 5.84% during the period 2015-2020 6, it significantly lags the rising cooling demand of the modern world.
New initiatives are required to introduce the new breed of technologically advanced evaporative coolers and improve their role in a sustainable development of the AC industry.
This article was written by Air2O’s Cannabis Cultivation Cooling Engineer, Iggy Kogan.
5. Medium Term Energy Efficiency Report
6. Global Evaporative Cooling Market. Mordor Intelligence, 2016